Apparatus for automatically administering anesthetics



y 1956 H. M. KIRSCHBAUM 2,7

APPARATUS FOR AUTOMATICALLY ADMINISTERING ANESTHETICS Filed June 29,1953 2 Sheets-Sheet l FIG.I.

MASK

I ANESTHETIC GAS OXYGEN GAS p INVENTOR. HARRY M.KIRSCHBAUM BY Wm W 1 3%ATTORNEYS July 17, 1956 H. M. KIRSCHBAUM 2,

APPARATUS FOR AUTOMATICALLY ADMINISTERING ANESTHETICS Filed June 29,1953 2 Shuts-Sheet 2 FIG.3.

INVENTOR.

HARRY M.K|RSCHBAUM M W+8M ATTORNEYS United States Patent APPARATUS FORAUTOMATICALLY ADMINIS- TERING ANESTHETICS Harry M. Kirschhaum, Detroit,Mich. Application June 29, 1953, Serial No. 364,980 4 Claims. (Cl.128-188) In general anesthesia produced by the administration of gaseousanesthetics, the oxygen content of the blood of the patient isdiminished and if carried beyond a certain point is dangerous, if notfatal. Correction of this condition can be made by administering oxygengas, but it is essential that this should be performed without delay.

My invention relates to automatic means for administering a gaseousanesthetic, and it is the primary object of the invention to accomplishthis without danger of diminishing the oxygen content in the blood ofthe patient beyond a predetermined point. This application forms acontinuation-in-part of my pending application, Serial No. 171,869,filed July 3, 1950, and now abandoned.

It is a further object to obtain a construction which alternativelyadministers oxygen gas, and in which the change from one gas to theother is automatically elfected by means responsive to the condition ofthe patient.

The invention therefore consists in the construction as hereinafter setforth.

In the drawings:

Fig. 1 is a diagram of the apparatus;

Fig. 2 is a cross section through the control means on line 2-2, Fig. 1;

Fig. 3 is a diagram for the amplifying means for the current directlyresponsive to the condition of the patient; and

Fig. 4 is an enlarged View of the calibrated meter and index forming thetrip mechanism.

Generally described the apparatus comprises a supply of anesthetic gas,a supply of oxygen gas, a hood or other means for administering gas tothe patient, a connection between each of said supplies and said hood,valve means reversable in successive operation thereof forsimultaneously opening one of said connections and closing the other,and vice versa, closing the first and opening the other, and meansautomatically responsive to the condition of the patient with respect tooxygen content of the blood for timing said successive reversal of saidvalve means.

Gas supply and controlling valve mechanism As shown in Fig. 1, A is aconduit leading from a container (not shown) for the anesthetic gas andB is a conduit from an oxygen supply. C and D are valves, respectively,in the conduits A and B, which valves are biased to automatically closebut are opened by electromagnetic means such as solenoids E and E. F isa conduit connected with the conduits A and B beyond the valves andleading to a mask, or other device, G for administering the gas to thepatient. The solenoid E of the valve C is included in an electriccircuit H and solenoid E of the Valve D is included in electric circuitH. Both circuits are controlled by a step-relay I so constructed thatwhen one circuit is closed the other will be open and vice versa. Asdiagrammatically illustrated the step-relay I has a movable contact Iand a pair of contacts I and I on opposite sides thereof. The contact Iis mounted on a lever 1 the free end of which is in contact with arotary cam I having 2,754,819 Patented July 17, 1956 ice alternatingraised and depressed portions I and I". I is a pawl lever engaging aratchet wheel I coupled by any suitable means (not shown) to turn thecam step by step, each actuation advancing it a distance equal to thatbetween the adjacent raised and depressed portions. An electromagnet 1actuates the pawl lever to turn the ratchet wheel i one notch and aspring I returns it to engage another notch of the ratchet wheel. Thearrangement is such that, when the lever I rests upon a projection I ofthe cam, the contact I will engage the contact I to close the electriccircuit H, thereby energizing the solenoid E to open the valve C. 0n theother hand, when the lever I engages a depression I of the cam, thecontact I will engage the contact I to close the electric circuit Henergizing solenoid E and opening the valve D. This movementsimultaneously deenergizing the solenoid E to close the valve C andthus, When one valve is open, the other is always closed.

Control means responsive to condition of patient of a portion of theanimal tissue through which blood is circulating, such as the lobe J 4of an car. A spring J clamps the member I in position so that the beamfrom the lamp passes through the tissue and the blood circulatingtherein. Oxygenized blood is more transparent to the beam than blooddeficient in oxygen so that electric current generated in thephotoelectric cell will vary in volume in correspondence to oxygencontent. The cell current passes through conductors K to an amplifier Land meter L in which latter an index hand L is moved in oppositedirections corresponding respectively to increase and decrease in theamplified current volume.

Control circuit for the relay I An electric circuit M from a source ofA. C. current includes a resistor M, an electromagnet 1 for the relay I,and also a thyatron tube N having a grid N. A branch electric circuit 0including a photoelectric tube 0, a resistor O and a potentiometer O isconnected to the grid N and is so adjusted that when a light beamimpinges on the tube 0 the grid N will be maintained a potential whichis negative with respect to the cathode of said tube, thereby preventingflow of current through the circuit M. A lamp P in a branch electriccircuit P is used for forming the beam impinging on the photoelectrictube 0, and these elements are arranged in connection with the meter Lon opposite sides of the plane of movement of the index hand L.Preferably the photoelectric tube is placed within the casing of saidmeter and the lamp P outside the same, the light passing through anaperture in the casing. Also, the positioning is such that a shield L onthe index hand L will momentarily intercept the beam of light at aselected point P in the travel of the index hand in either direction.Thus, when the shield intercepts the beam, flow of current through thetube 0 is cut off and the negative potential of the grid N will changeto the potential of the cathode of said tube. This immediately startsflow of current through the circuit M and operates the step-relay I toclose one of the circuits H, H and open the other. The continuingmovement of the index hand removes the shield reestablishing the lightbeam and again placing a negative potential on the grid N, therebystopping flow of current through the tube N. The valve C and D are eachbiased to close and this will occur when their respective circuits H andH are opened. It will thus be apparent that the interception of thelight beam by the shield L forms an instantaneous trip mechanism forreversing the valves C and D.

As the modification in the oxygen content of the blood takes place inthe lungs of the patient and, as a time interval is required for themodified blood to reach the instrument I, there will be a lag in theoperation of the valves. However, by properly setting the instrument,the valves will be reversed before the oxygen content is dangerously lowto cut off the anesthetic gas and supply oxygen. After such reversal theindex L and shield L will continue to move in the same direction for abrief interval, which will again expose the tube to the light beamthereby cutting off current in the electromagnet 1 and permitting thespring I to return the pawl lever for engaging another notch in theratchet wheel I Upon the return movement of the index L (to the right inFig. 1) the shield L will once more cut oif the light beam and as aresult the magnet I will be energized to actuate the pawl lever I andmove the ratchet wheel I and cam 1 In brief the overrunning of the indexand shield merely returns the pawl lever to engage another notch, and itis only the return movement of said index and shield which producesanother actuation of the cam. It will thus be understood that anyfluttering action of the valves is avoided and each successive actuationis spaced by a timed interval from a preceding actuation.

The amplifier for the variable current from the cell I may be of anysuitable construction but, as specifically shown in Fig. 3, is asfollows: Q is a transformer and rectifier from which extend positive andnegative leads Q and Q each preferably of a potential of 150 volts. Athird lead Q from a voltage regulator Q has a positive potential of 75volts. T, T and T are triode tubes, the plates of which are connectedthrough suitable resistors R, R and R with the lead Q. The cathodes ofthe tubes T and T are connected to the negative lead Q through resistorsR R and R The plate of the tube T is connected through a resistor R withthe lead Q and the cathode of said tube is connected to the grid of thetube T and being also connected to a grounded resistor R and a capacitorS. The photo-cell I has connected thereto through a resistor R the leadQ and also connects to the grid of the tube T, which latter has a groundleak resistor R. A potentiometer S connected to the lead Q forms a meansfor varying the voltage on the grid of the tube T so as to balance thisup with the tube T. The meter L is in a bridge connection between theplates of the tubes T' and T With the hook-up just described, adjustmentmay be made prior to the administration of the anesthetic to compensatefor variables, such as individual variation in light transmissionthrough the ear of the patient to the photoelectric cell I. The meter Lis calibrated from to indicating progressive decrease in oxygen contentof the blood. An aperture in the wall of the meter casing located at thepoint P which is near to eighty of the calibrations permits light fromthe lamp P to impinge on the photo-electric tube 0, but as beforeexplained, the light beam will be momentarily cut off when the shield Lof the index L registers with said aperture. This forms the trip meanstiming the reversals from one gas to the other.

What I claim as my invention is:

1. Apparatus for administering anesthetics comprising a gasadministering mask for the patient having connections thereto,respectively for an anesthetic gas and for oxygen, valve meanscontrolling said connections adapted to open one and close the other andalternately to open the latter and close the former, means for operatingsaid valve means to reverse the same in each successive operationthereof, and means automatically responsive to the condition of thepatient as to oxygen content of his blood for timing said successiveoperations.

2. The construction as in claim 1 in which said means responsive to thecondition of the patient varies an electrical current, a meter for saidcurrent including an index hand, means for directing a beam of lightacross the path of said hand located at a predetermined point in therange of movement thereof, a photo-electric tube in the path of saidbeam controlling said operating means, and a shield on said index handfor momentarily interrupting said light beam, thereby actuating saidvalve operating means.

3. The construction as in claim 2 in which said meter has an enclosingcasing also enclosing said photo-electric tube with an aperture in saidcasing for the passage of said light beam therethrough from an outsidesource, said shield momentarily registering with said aperture in themovement of said index hand.

4. The construction as in claim 2 provided with a1nplifying means forthe variable current in advance of said meter.

References Cited in the file of this patent UNITED STATES PATENTS2,185,067 Sholes Dec. 26, 1939 2,414,747 Kirschbaum Jan. 21, 19472,442,462 Kirschbaum June 1, 1948

